#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

int f(char *p, int n) {
    for (int k = n; k > 0; k--) {
        for (int i = 0; i < n - k + 1; i++) {
            int i1 = i + k - 1, b = 1;
            for (int j = 0; j < k / 2; j++) {
                if (p[i + j] != p[i1 - j]) {
                    b = 0;
                    break;
                }
            }
            if (b) return k;
        }
    }
}

void g(int n, int t) {
    char p[100] = {};
    p[0] = '0';
    for (int k = 0; k < 1 << (n - 1); k++) {
        for (int i = 1; i < n; i++) {
            p[i] = '0' + (k >> (i - 1) & 1);
        }
        if (f(p, n) == t) {
            cout << p << endl;
            return;
        }
    }
    cout << -1 << endl;
}

int main() {
    int n, k;
    cin >> n >> k;

    if (n < 10) {
        g(n, k);
        quick_exit(0);
    }

    if (k < 4) {
        cout << -1 << endl;
        quick_exit(0);
    }

    for (int i = 0; i < k; i++) {
        cout << '0';
    }
    for (int i = 0; i < n - k; i++) {
        cout << "101100"[i % 6];
    }
    cout << endl;

    return 0;
}